Ruby Tojo is a witch from the human world who was part of a plot to destroy mankind as a response to a large garbage dump polluting her mistress' sanctuary. Her hate for humans stems from a car accident caused by a human drunk driver that took her parents' lives while the family was vacationing in the human world. Upon remembering the kind of love her parents had given her, she attempts to persuade her mistress to call off her plan but to no avail, as her mistress was bent on destroying the human world. She recuperated at Yokai Academy after her mistress is defeated and put to rest, and reappears when Tsukune becomes out of control as a ghoul, aiding Mikogami in sealing his abilities. She now resides at Yokai Academy as Mikogami's aide, and continues to work for him in the second manga serialization. Despite not being an official student, she receives permission to become a member of the Newspaper Club as its assistant advisor (though she prefers to take orders). Exclusively in the anime, a running gag involves her randomly switching positions to help the school. When asked why, she states "many many things" have happened, though it is believed these are orders from Mikogami as a debt of gratitude for providing her with a new magic wand. Her original outfit in the Witch's Knoll arc consists of a black sleeveless top with an exposed midriff and a long orange skirt, though she later switches to a gothic lolita outfit after she fully recovers from her injuries.
It is later revealed in an omake that the reason why Ruby works under Mikogami is because of her infatuation with Tsukune, and by working at the academy, she could be near him.[volume & issue needed] The anime omits the presence of her master or the inclusion of her parents, drastically changing the events surrounding her, including the reasons behind her return. Most of Ruby's magic revolves around a motif of ravens and flora, both as familiars and alternate forms for her to take, such as the ability to grow six raven wings on her back that allow her to fly. Ruby can use these wings as an offensive weapon using its razor-sharp feathers, and can restrain her opponents with them as well, such as the case when she restrains Inner Moka just when the latter was about to kill Tsukune when he becomes out of control as a ghoul. Apparently, Ruby has shown that she is a masochist and the biggest pervert of them all during a training exercise for Tsukune to control his ghoul powers, even admitting to Tsukune a desire to be his "toy".